Core type hammer drill with annular piston



Aug. 18, 1970 G. KLEMM CORE TYPE HAMMER DRILL WITH ANNULAR-PISTON Filed 001.

U.S. Cl. 175-92 2 Claims ABSTRACT F THE DISCLOSURE A core-type deep-drilling hammer drill, especially for carrying out core drilling in rock, having an annular core bit, a core barrel and a core-catcher ring, wherein on the drill hole Ifloor a hollow piston is provided as striker element which is guided between an inner cylinder, serving at the same time as core barrel, and an outer cylinder resting on the inner side of the external housing and clamped in between annular core bit and an upper part, and which acts upon the rear end of the core bit. The piston is driven by air, which also ushes cuttings from the core bit.

BACKGROUND OF THE INVENTION This invention relates to core-type deep-drilling hammer drills, especially for carrying out core drilling in rock, having an annular core bit, a core barrel and a core catcher ring.

Hitherto it was usual and necessary to use diamond core bits for the execution of core drillings, for example for soil and rock-exploration. Drilling had to beetlected with high pressure application and high rotation speed. Only water could be yused for the flushing, so that it was necessary to ensure an adequate supply of water. Moreover it was essential to withdraw the whole drill linkage after relatively short drilling distances (after about 1.5 metres each time) in order to recover core pieces, which lresulted in a drilling depth per day of only 10 to 15 metres, in the case of rotary drilling.

SUMMARY OF THE INVENTION It is the problem of the invention to rationalise the execution of core drilling in rock considerably by the provision of a core-type deep-drilling hammer drill and to make it possible in place of the expensive diamond core bits to use hard metal core bits now which are substantially cheaper as regards wear and for which air flushing is adequate, so that daily drilling depths of 0 to 60 metres are achievable.

According to the invention this is achieved primarily due to the fact that a hollow piston is provided as striker element on the floor of the drill hole, which piston is guided between an inner cylinder, serving at the same time as core barrel, and an outer cylinder resting upon the inside of the external housing and clamped in between the annular core bit and an upper part, and acts upon the rear end of the core bit.

According to the invention, at the front end a clamping ring can be screwed into the external housing for the clamping-in of the outer cylinder and of a piston-guide bush, the clamping ring being provided with passage holes for flushing air. The annular core bit can here be inserted into the clamping ring.

The core-catcher ring known per se can be inserted according to the invention with axial play into a ring groove of the annular core bit.

A ntter valve device is provided according to the invention for the control of the hollow piston.

A flutter feature of the invention consists in that for the connection of the rst extension rod a double-walled intermediate piece is provided having an annular threaded United States Patent O 3,524,511 Patented Aug. 18, 1970 insert piece with conical internal threading in which an insert piece with corresponding conical external threading seated in the lower end of the extension rod engages. These insert pieces have passage bores for compressed air and flushing air, distributed in the peripheral direction.

A distance ring, likewise having passage bores distributed in the peripheral direction, is expediently welded into the lower end of the intermediate piece.

B-RIEF DESCRIPTION OF THE DRAWING The invention will now be explained in greater detail with reference to the accompanying drawing, which illustrates by way of example a longitudinal section through a core-type deep-drilling hammer drill according to the invention.

DESCRIPTION OF THE PREFERRED IEMBODIMENT As shown in the drawing, the hammer drill represented in section comprises essentially an external housing 1, an annular core bit 2. with hard metal cutting edges 3, an inner cylinder 4 serving at the same time as core barrel, for the guidance of a hollow piston 5, and an outer cylinder 6 which externally guides the hollow piston 5. For further guidance of the hollow piston 5 a guide bush 7 is also provided. A clamping ring 8, which is provided with passage holes 9 for ilushing air, is screwed into the lower end of the external housing 1. The clamping ring 8 holds the outer cylinder 6 and the guide bush 7 fast in their position. The annular core bit 2 can be screwed into the clamping ring 8, as illustrated, or can equally be held therein by a known key connection. A corecatcher ring 11, which is slit longitudinally at one point of the periphery and can be resiliently compressed in insertion, is seated in a ring groove 10 in the annular core bit 2. The neck piece 12 of the annular core bit 2 is prolonged so far that a narrow interspace 13 remains between the core bit 2 and the clamping ring 8, into which interspace there open longitudinal grooves (not shown) when the latter moves back and forth.

Several, for example two, through-passing longitudinal grooves (not shown in the sectional drawing) are situated in the outer face of the outer cylinder 6, which grooves constantly convey flushing air by way of the passage holes 9 of the clamping ring 8 to the outside of the annular core bit 2. Furthermore the outer cylinder 6 comprises grooves 15 which are downwardly closed and supplied with compressed air through an oblique bore 16 of a flutter-valve device 17, which air passes by way of an opening 18 in the outer cylinder 6 into the lower cylinder chamber 19, in order to charge the hollow piston 5 from beneath. Further grooves 20 of the outer cylinder 6 are downwardly open and in communication there with grooves 21 of the guide bush 7. When the hollow piston 5 reaches its lower position (it is represented in the drawing approximately in its middle position), the pressure in the upper cylinder chamber 22 is released through openings 23 which constitute a connection with the grooves 20, so that the compressed air escaping from the upper cylinder chamber 22 passes as flushing air to the annular core bit 2. When the upper cylinder chamber 22 is relieved of pressure, the pressure acting upon the smaller cross section of the under side of the hollow piston 5 can move the hollow piston 5 back or upwards again, until the air-outlet openings 23 are closed again by the piston 5, so that now the pressure acting upon the larger upper side of the piston 5 moves the piston 5 downwards again, until it strikes upon the rear end of 3 the neck piece 12 of the annular core bit 2. The upper cylinder chamber 22 is supplied with compressed air by the Hutter-valve device 17 through bores 24, while the compressed air is fed to the flutter-valve device 17 through bores 2S.

The bores 25 are connected to the spaces above and below the diaphragm of the valve 17. Compressed air flows through one of the bores 25 to the space below the diaphragm and forces the diaphragm upwards to open the connection between said bore 25 and the chamber 22 and simultaneously to close the connection between a further bore 25 and the bore 16. When communication is established between the chamber 22 and the openings 23 the diaphragm is forced downwards by the air from said further bore 2S thereby closing the connection to the chamber 22 and opening the connection to the bore 16. When the communication between the chamber 22 and openings 23 is cut ofic the diaphragm is moved upwards again. The hollow piston S in this way moves back and forth in rapid sequence and thus, by means of the annular core bit 2, effects comminution of the rock, which is conveyed away by the rotating core bit 2 and by the flushing air.

Since the hollow piston acting as striker element is situated practically on the floor of the drill hole, the impact loading of the annular core bit 2 is undiminished in its intensity even at very great drill hole depths. The core drilling can be carried out to the desired depth without the need to take the core out every time after short drilling distances. Due to the percussion drilling, which renders the use of hard metal annular core bits possible, the Wear is reduced to a minimum. The flushing air effects such intensive cooling of the annular core bit 2 that in cold, damp weather it is even possible for icing of the bores 9 of the clamping ring 8 to occur, as has appeared in practice. It is possible to avoid this however by appropriate frost-protection means.

At the upper end of the core-type deep-drilling hammer drill a double-walled intermediate piece 26 is screwed into the external housing 1, by means of which piece the first extension rod 27 can be attached. The intermediate piece 26 comprises an annular threaded insert piece 28 having conical internal threading, in which a correspondingly conically externally threaded insert piece 29 seated in the lower or forward end of the extension rod 27 engages. The insert pieces 28 and 29' possess passage bores 30 distributed in the peripheral direction for compressed air and flushing air, while an annular space 31 ensures a connection between the passage bores 30 even if these should not be in alignment with one another when the extension rod 27 is screwed in. A distance ring 32, which likewise is provided with passage bores 33 distributed in the peripheral direction, is welded into the lower end of the intermediate piece 26. On withdrawal of the Whole drill linkage and unscrewing of the individual extension rods 27, each of lwhich has in its rear end a threaded insert piece corresponding to the threaded insert piece 28 of the intermediate piece 26, the cores seated in these can be recovered.

It is self-evident that the present core-type deep-drilling hammer drill can be used not only for core drilling, but also for normal drilling.

What is claimed is:

1. A core drill comprising an elongated tubular casing having an upper and a lower section and having first and second passage means; a drill bit mounted on said lower section of said casing for rotation with said casing and being dimensioned and axially fixed to said casing so that said casing will follow said drill bit down a hole being drilled; tubular means mounted within said casing to provide a continuously unobstructed passage between said drill bit and the top of said casing and being dimensioned to be spaced from said casing to define an annular space; piston means mounted for axial movement within said annular space; passage means for delivering pressurized fluid to said piston means and for letting off relieved fluid to said drill bit, respectively; and annular valve means disposed between said casing and said tubular means for controlling the flow of pressurized uid to said annular space and said passage means, respectively, to cause said piston means to hit said drill bit and to cause fluid to flush said drill bit.

2. A core drill comprising: an elongated tubular casing having a thinner walled upper section and a thicker walled lower end section; said thinner walled section being provided with first and second channel means; said first channel means leading to first openings in the lower part of said thinner walled section and said second channel means, beginning with second openings in the medium part of said thinner Walled section and being connected to said third'channel means; a drill bit having a thinner walled, a tapered and a thicker walled portion, said thinner walled portion being mounted within said thicker walled end section of said casing for rotation with said casing, the periphery of said tapered portion being in connection with said third channels; said thicker walled portion being dimensioned and said thinner walled portion being axially fixed to said casing so that said casing will follow said drill bit down a hole being drilled; tubular means mounted within said casing to provide a continuously unobstructed passage between said drill bit and the top of said casing and dimensioned to be spaced from said thinner walled portion of said casing to define a first annular space of a larger diameter and being spaced from said thicker Walled end section to define a second annular space of a smaller diameter; piston means having a first portion for axial movement within said first annular space and a second portion for axial movement within said second annular space; and annular valve means disposed between said casing and said tubular means for controlling the flow of pressurized fluid to said first annular space and said first channel means, respectively, to cause said piston means to move up and down to hit said drill bit and to exhaust fluid through said second and third channel meanss to flush said drill bit.

References Cited UNITED STATES PATENTS 1,087,632 2/1914 Benjamin 175-100 X 1,834,583 12/1931 Mitchell 175-255 X 3,075,589 l/1963 Grable et al. -215 3,207,240 9/ 1965 Hgel 175-249 X 3,299,971 1/ 1967 Lewis 175-92 MARVIN A. CHAMPION, Primary Examiner I.'A. CALVERT, Assistant Examiner Us. C1. xn. 

